With brother Donald, runs massive privately held media conglomerate Advance Publications, built up from newspaper properties their father Sam started buying in the 1930s. Pair took over after Sam's death in 1979, expanded and diversified. Now run Bright House Cable (2 million subscribers) and own pieces of the Discovery Channel and Learning Channel. "Si" heads magazines (New Yorker, Vanity Fair, Vogue) under Condé Nast.